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Effects of Elevated CO<sub>2</sub> on Wheat Yield: Non-Linear Response and Relation to Site Productivity

Author:
Broberg, Malin C., Högy, Petra, Feng, Zhaozhong, Pleijel, Håkan
Source:
Agronomy 2019 v.9 no.5
ISSN:
2073-4395
Subject:
Triticum aestivum, carbon, carbon dioxide enrichment, crop models, food production, food security, fumigation, grain yield, meta-analysis, photosynthesis, rooting, wheat, yield components
Abstract:
Elevated carbon dioxide (eCO<inf>2</inf>) is well known to stimulate plant photosynthesis and growth. Elevated carbon dioxide&rsquo;s effects on crop yields are of particular interest due to concerns for future food security. We compiled experimental data where field-grown wheat (Triticum aestivum Linnaeus) was exposed to different CO<inf>2</inf> concentrations. Yield and yield components were analyzed by meta-analysis to estimate average effects, and response functions derived to assess effect size in relation to CO<inf>2</inf> concentration. Grain yield increased by 26% under eCO<inf>2</inf> (average ambient concentration of 372 ppm and elevated 605 ppm), mainly due to the increase in grain number. The response function for grain yield with CO<inf>2</inf> concentration strongly suggests a non-linear response, where yield stimulation levels off at ~600 ppm. This was supported by the meta-analysis, which did not indicate any significant difference in yield stimulation in wheat grown at 456&ndash;600 ppm compared to 601&ndash;750 ppm. Yield response to eCO<inf>2</inf> was independent of fumigation technique and rooting environment, but clearly related to site productivity, where relative CO<inf>2</inf> yield stimulation was stronger in low productive systems. The non-linear yield response, saturating at a relatively modest elevation of CO<inf>2</inf>, was of large importance for crop modelling and assessments of future food production under rising CO<inf>2</inf>.
Agid:
6469679